1. Technical Field
The present disclosure relates to a photographing optical lens. More particularly, the present disclosure relates to a compact photographing optical lens applicable to electronic devices.
2. Description of Related Art
In recent years, with the popularity of electronic devices having camera functionalities, the demand of miniaturized optical systems has been increasing. The sensor of a conventional optical system is typically a CCD (Charge-Coupled Device) or a CMOS (Complementary Metal-Oxide-Semiconductor) sensor. As the advanced semiconductor manufacturing technologies have allowed the pixel size of sensors to be reduced and compact optical systems have gradually evolved toward the field of higher megapixels, there is an increasing demand for compact optical systems featuring better image quality.
A conventional optical system employed in a portable electronic product mainly adopts a four-element lens structure or a five-element lens structure. Due to the popularity of mobile terminals with high-end specifications, such as smart phones, tablet personal computers and wearable apparatus, the requirements for high resolution and image quality of present compact optical systems increase significantly. However, the conventional optical systems cannot satisfy these requirements of the compact optical systems.
Other conventional compact optical systems with six-element lens structure are disclosed. However, the refractive power and the surface shape of the lens elements are not favorable for enhancing the diverging ability at the image side and reducing the back focal length of the optical system. Furthermore, the converging intensity at the optical axis cannot be moderated for enhancing the image sharpness. Accordingly, it is not favorable for keeping the optical system compact and enhancing the image quality.